Radiography Flashcards
Frequency vs Wavelength
Inversely Proportional
* greater frequency = shorter wavelength
Ionizing Radiation
Type of energy transfer found with x-rays
* ions produced when energy passed through matter
* net positive charge
RAD
Measures energy transferred by radiation to body part
* absorbed dose
* unit is gray (Gy) = 100 rad
REM
Dose equivalent
* how radiation affects each tissue
* unit is Sievert (Sv) = 100 rem
Radiation Safety
3 Rules
- Time
- Distance
- Shielding
kV
Controlled by autotransformer
* increases voltage to produce x-rays
* controls acceleration of electrons
* only adjust according to tissue size (penetrating ability)
* increased = low contrast (more shades)
mA and mAs
- mA = controls current
- mAs = controls blackening / density of image
- Use to fine-tune image = minimize motion by setting this high with short time
- Increased = darker image
Cathode
- Negative charge
- Source of electrons
- Thicker part of animal should be closer to here
Anode
- Positive charge
Focal Spot
- Found on the anode side
- Area where electrons are attracted
- Smaller focal spot = sharper image but heat more concentrated
Grid
- Used when area is thicker
- Prevents scatter radiation from reaching film
- Absorbs part of primary beam - need to have higher mAs or kV
Tissue Density
Low to High
- Gas
- Fat
- Water
- Organs
- Muscle
- Bone
- Metal
Film Processing Steps
- Developing
- Rinsing / Stop bath
- Fixing
- Washing
- Drying
Developer
Reduces / converts exposed silver crystals to black
* more converted crystals = darker image
* unconverted crystals get washed away by fixer
Rinse
Stops the developing process
